Death

"My men dishonor me. But it is fitting that I kill you myself. You two! Leave us! I am going to enjoy thrusting my sword into you."

―Kazuki confronting Toni.

Toni later attacks Kazuki's casino, killing many of his men, and facing him in a sword duel, resulting Kazuki's death. After learning of her husband's death, Toshiko, feeling remorse, commits suicide. After his death, his siblings become the new co-leaders of the Yakuza.

Trivia

During the mission A Date With Death, Toshiko states that Kazuki is a samurai. Kazuki is likely to either be a descendant of a samurai or to follow the Bushido code practiced by the Yakuza, becoming a samurai by way of practice and nickname. The official title as a military nobleman was abolished during the Meiji Restoration during the nineteenth century.

It is sometimes alluded to that Kazuki is a closeted bisexual. When Toshiko tells Toni that Kazuki "prefers the company of his men", she then asks "Do you understand, Mr. Cipriani?". Toni later teases Kazuki when he says "I am going to enjoy thrusting my sword into you", to which Kazuki does not respond, and soon after tries to have Toni killed outside of his samurai code of honor.

Furthermore, on the game's official website, an email is shown from Kazuki to Kenji, saying he feels very guilty about something he isn't telling Toshiko. He writes "Many times, I have killed a man, afterwards, just to keep him quiet", and that "now there is someone special, but I am a man, not a rat, skulking in a sewer". Toshiko discovers the email and sends it to an anonymous forum for life advice.

During the final duel with Kazuki on the heli pad, after losing some health he will call his bodyguards, which are armed with deadly M4 rifles, to attack player. This may cause player's instant death. However, with a katana, player can directly behead Kazuki and his bodyguards will disappear. So using katana againest Kazuki is strongly recommended.